FOR UNDERTAKING to normalize relations with China, Jimmy Carter said he expected "massive applause throughout the nation." What he is getting from the Congress is something less resounding but more valuable: language expressing the American concern for Taiwan in terms more meaningful than his own. The chosen vehicle is the administration's bill setting up the necessary new framework for future dealings with Taiwan. That bill said nothing about security, but the Senate Foreign Relations Committee added language that does and the House Foreign Relations Committee is doing the same.

Now, Mr. Carter cannot fairly be charged with utter indifference to Taiwan. He did not "abandon" the island; he merely terminated a defense treaty under its provisions. He pledged continued fidelity to Taiwan's well-being and has moved to make specific arrangements -- arms sales, a new unofficial framework for continuing old official ties -- to make good on that pledge. Peking lacks the physical means and, its leadership contends, the political intent to do Taiwan harm, and even if those conditions changed, the United States would remain in a position to take action, with or without a defense treaty. A good case can be made that normalization offers a better ultimate guarantee for Taiwan than would the perpetuation of ties established in another era.

But Mr. Carter can fairly be charged with indifference to Congress, and this is no small thing. It is not merely that he wounded certain sensibilities on Capitol Hill by inadequate consultation during the runup to normalization in December. That could be excused by the need to keep the talks with Peking on track.The more serious flaw was not to realize that normalization and its reverse side, the establishment of a new pattern for Taiwan, could only be enhanced if they were seen to reflect an informed congressional imprimatur as well as a presidential one. It is a question of credibility -- of Peking and Taiwan alike understanding that the United States means to keep its word. Any change as large as normalization is bound to raise the question, and the assertion of congressional concern strengthens the administration's own.

Frank Church, in his first substantive test as chairman of the Senate Foreign Relations Committee, brought off Taiwan-security language that did two things. This language, adopted unanimously, will surely be more impressive to Peking for reflecting a broad congressional consensus and not a narrow or partisan majority. Moreover, the language protects well the essential feature of normalization with Peking -- not to maintain a backdoor recognition of Taipei, as some would-be spoilers of normalization had wanted to do. That is why the administration, which started out by saying that no additional congressional handiwork was necessary, now finds that the Senate committee's product is acceptable after all. The House is, as we say, heading in the same direction.

Mr. Carter might have done better if he had understood and accepted earlier the extra weight that informed congressional cooperation could add to his own chosen China policy. It would have saved him some slight political embarrassment. But the way seems clear now for a truly national expression of policy on this important question.